I. Field
The present disclosure relates generally to wireless communications and more specifically to providing HARQ functionality for system access communications.
II. Background
Wireless communication systems are widely deployed to provide various types of communication content such as, for example, voice, data, and so on. Typical wireless communication systems may be multiple-access systems capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, . . . ). Examples of such multiple-access systems may include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, and the like. Additionally, the systems can conform to specifications such as third generation partnership project (3GPP), 3GPP long term evolution (LTE), ultra mobile broadband (UMB), and/or multi-carrier wireless specifications such as evolution data optimized (EV-DO), one or more revisions thereof, etc.
Generally, wireless multiple-access communication systems may simultaneously support communication for multiple mobile devices. Each mobile device may communicate with one or more base stations via transmissions on forward and reverse links. The forward link (or downlink) refers to the communication link from base stations to mobile devices, and the reverse link (or uplink) refers to the communication link from mobile devices to base stations. Further, communications between mobile devices and base stations may be established via single-input single-output (SISO) systems, multiple-input single-output (MISO) systems, multiple-input multiple-output (MIMO) systems, and so forth. In addition, mobile devices can communicate with other mobile devices (and/or base stations with other base stations) in peer-to-peer wireless network configurations.
Automatic repeat/request (ARQ) technologies, such as hybrid-ARQ (HARQ), can be used between mobile devices and base stations to facilitate successful communications. For example, the base station can transmit signals to a mobile device, and the mobile device can transmit control data back to the base station indicating whether or not it successfully received data within the signal. If not, the base station can retransmit the signal. To this end, devices utilizing HARQ can have a HARQ entity that receives the data and determines whether it is a new transmission or retransmission based on a new data indicator (NDI) in the data. NDIs, however, are not always present in transmissions between the mobile devices and base stations, particularly for system access communications.